A number of intravascular procedures are currently utilized to treat a stenosis within a body vessel of a human being. A common intravascular procedure is referred to a percutaneous transluminal coronary angioplasty (hereinafter "angioplasty"). During a typical angioplasty procedure, a guidewire is initially positioned within the body vessel and a guiding catheter is positioned over the guidewire. Next, a balloon catheter having an inflatable balloon is advanced through the guiding catheter and vessel until the balloon is adjacent to the stenosis. Subsequently, inflation of the balloon compresses the stenosis and dilates the body vessel.
Typically, the body vessel is curved and has a relatively small inner diameter. Therefore, a physician often needs to rotate a distal end of the catheter to navigate through the curved body vessel. As a result thereof, the medical catheter must have good torsional strength so that the distal end of the catheter rotates upon rotation of a proximal end of catheter. Presently, most guiding catheters include a catheter shaft having flexible inner liner, a braided wire mesh wrapped around the inner liner and a flexible outer shell. The braided wire mesh and the outer shell are relatively stiff and provide torsional strength to the catheter shaft. Unfortunately, the distal end of the catheter shaft is also relatively stiff and the catheter shaft is often difficult to move in the vessel.
One attempt to solve this problem involves adding one or more separate, tubular, soft tips onto the distal end of the catheter shaft. The soft tips are made of a polymer having a lower hardness than the catheter shaft. Unfortunately, the transition from the catheter shaft to the soft tip is relatively stiff and inflexible. Further, the transition between the relatively hard catheter shaft and the soft tip is subject to collapse and kinking during movement in the vessel. As a result thereof, this solution is not entirely satisfactory.
In light of the above, it is an object of the present invention to provide an improved medical catheter having relatively good movement and tracking in the body vessel. Another object of the present invention is to provide a medical catheter having a good transition between the relatively stiff catheter shaft and a flexible soft tip. Still another object of the present invention is to provide a medical catheter having good flexibility, durability, and torsional strength characteristics. Yet another object of the present invention is to provide a medical catheter which is relatively easy and inexpensive to manufacture.